Abstract 19545: Prdm16 Deficiency Leads to Arterial Vascular Defects by Modulating the Activity of the Notch Signaling Cascade
Aims: We recently identified the transcriptional co-regulator PRDM16 as a key component of a unique transcription factor code driving human arterial endothelial specification in vitro. We tested whether PRDM16 exerts a similar role in vivo using zebrafish as a readout model.
Results: In zebrafish embryos, prdm16 was uniquely expressed in the arterial branch of the vascular system. Moreover, morpholino-based knockdown of prdm16 resulted in the emergence of dose-dependent arterial vascular defects. Intriguingly, these anomalies coincided with reduced canonical Notch activity in the dorsal aorta of prdm16 morphants as evidenced by loss of GFP signal in the Tg(TP1:eGFP) reporter line. In agreement with these findings, overexpression of PRDM16 in HUVEC elevated mRNA levels of the Notch ligand DLL4 and the Notch transcriptional effectors HEY1 and HEY2 in a NotchICD-dependent manner. Vice versa, excess NICD release by adding recombinant hDll4 to these cells potentiated the PRDM16-mediated Notch induction. Furthermore, PRDM16 overexpression also led to enhanced activity of the NICD-RBPJκ transcriptional complex in these cells. In concordance with the latter, treatment with the canonical Notch inhibitor DAPT aggravated the aortic hypoplasia seen in prdm16 morphants. Similar results were observed with concomitant knockdown of both prdm16 and rbpj. Mechanistically, we demonstrated that PRDM16 physically and functionally interacts with the current gold standard for arterializing endothelial cells, HEY2. Indeed, co-IP experiments indicated that PRDM16 directly binds HEY2. Finally, partial knockdown of prdm16 evoked a localized arterial (aortic) defect resembling aortic coarctation in zebrafish heterozygous for the recessive gridlock (grlm145) mutation, a phenotype normally only typically seen in homozygous grlm145 embryos.
Conclusion: Our data demonstrated that PRDM16 might be vital for proper arterial development, similar to HEY2, and that both proteins could reside in the same transcriptional complexes. However, further studies are warranted to determine whether mutations in PRDM16 occur in patient cohorts with arterial malformations and whether PRDM16 constitutes a novel therapeutic target for arterial disorders.
Author Disclosures: M. Beerens: None. S. Craps: None. C. MacRae: None. A. Luttun: None.
- © 2016 by American Heart Association, Inc.